Carotenoids are plant pigments responsible for bright red, yellow and orange hues in many fruits and vegetables. These pigments play an important role in plant health. People who eat foods containing carotenoids get protective health benefits as well. Carotenoids are a class of phytonutrients ("plant chemicals") and are found in the cells of a wide variety of plants, algae and bacteria. They help plants absorb light energy for use in photosynthesis. They also have an important antioxidant function of deactivating free radicals â€” single oxygen atoms that can damage cells by reacting with other molecules, according to the Linus Pauling Institute at Oregon State University. Carotenoids also act as antioxidants in the human body. They have strong cancer-fighting properties, according to the Physicians Committee for Responsible Medicine. Some carotenoids are converted by the body to vitamin A, which is essential to vision and normal growth and development. Carotenoids also have anti-inflammatory and immune system benefits and are sometimes associated with cardiovascular disease prevention.